# ADR-0004: Use Email Confirmation for Reservations

Date: 2026-04-28

## Status

Accepted

## Context

Public visitors can request seats for a specific performance. The system needs a simple way to verify that the requester controls the provided email address before issuing a confirmed reservation and QR code.

The system also needs to avoid overbooking when multiple pending reservations exist for the same performance.

## Decision

Create reservations as `pending` first, then send an email confirmation link containing an opaque confirmation token.

A reservation becomes `confirmed` only when the confirmation link is opened and the backend validates the token. Final capacity validation happens during confirmation inside a database transaction. A QR code is generated only after successful confirmation.

## Consequences

- Visitors receive a clear confirmation step before the reservation is finalized.
- Mistyped or unreachable email addresses are less likely to consume capacity.
- Pending reservations do not guarantee seats.
- A visitor may lose availability if other reservations are confirmed before they open the confirmation link.
- The booking flow depends on email delivery working reliably enough for the audience.